const tree = function(lists) {
	const data = JSON.parse(JSON.stringify(lists));
	const result = []
	if (!Array.isArray(data)) {
		return result
	}
	data.forEach(item => {
		delete item.children
	})
	const map = {}
	data.forEach(item => {
		map[item.id] = item
	})
	data.forEach(item => {
		const parent = map[item.pid];
		if (parent) {
			(parent.children || (parent.children = [])).push(item)
		} else {
			result.push(item)
		}
	})
	return result;
}

export default tree;
